1. Field of the Invention
The present invention relates to oil and gas well drilling and more particularly relates to the management of oil and gas well drilling fluids. Even more particularly, the present invention relates to a method and apparatus for transporting bulk quantities of dry drilling material to and from an oil and gas well drilling structure and wherein an improved silo apparatus is used for transporting drilling additives to the well drilling site in dry powder form, and the handling of such dry material in dust-free form, using inert gas to both preserve the dry product and to transmit the dry product from the silo, and wherein the silos are maintained in a positive pressure and in arid condition to prevent moisture from entering the silo.
2. General Background
There are many dry powder products used as drilling mud components. Many of these products are extremely reactive in the presence of moisture. Some of these dry powders such as barite (a mined ore) are not affected by moisture. Other products such as XCD-Polymer are extremely hydrophilic and must be shipped in small packages, sacks, or the like which are expensive to produce and a nuisance once empty. When alternate forms of transportation for these polymers have been attempted, the best attempt at a solution has been to slurry them in nonpolar, environmentally hazardous liquid carrier and transport them to the drilling location via a liquid bulk tank.
Manufacturers spend a large amount of time and money in the handling of equipment and personnel to place such dry products in sacks or bags and to load those onto a drilling rig at significant cost to the end user. Once sacks or bags are filled with such dry material, they are typically loaded onto wooded pallets or the like and then shrink-wrapped with a plastic film for protection against the elements. The shrink-wrap is very expensive and can be easily torn or punctured exposing the product to the environment, sometimes resulting in damage or destruction of the product before end use. Often times the damage is discovered at a critical time when the ruined inventory is needed for maintaining a rig operating condition.
Palletized materials are handled with fork trucks and cranes in transporting those materials from the source, through vehicles and vessels to the well drilling site. Palletized material is often placed upon a large work vessel for marine transport. Palletized drilling materials can be damaged by the fork truck, the crane, or by improper handling techniques. Sometimes, the damage is not noticed and the product is shipped with all attentive expense to the drilling site in damaged condition. This commonly happens when a forklift operator damages sacks of material which are loaded onto a pallet and never notices the damage until the product is unloaded from the pallet on the drill rig.
If the product is delivered to a land based drilling rig, it will be off loaded using a forklift. The land location is often surrounded by wooden board roads in some locations, thus making fork truck operation more difficult. Entire pallets of products have been dropped due to unstable conditions on such wooden board roads.
If palletized drilling products arrive at a sea port, they are generally off loaded by a crane. The equipment used to pick up the pallets has tongues which slide under the pallet with cables and straps. When the lift is made, the cable becomes tight and can cut through the shrink wrap into the paper sacks. In situations such as this, the product is then exposed to the elements and can become moist or simply drain out of the sacks after the damage is done. Sometimes, if many sacks are punctured during lifting operations, the load can become imbalanced and the entire pallet of packaged product can be spilled and lost. Bodily injury can occur as a result of such accidents. In rough seas, the unloading of palletized bags of dry drilling material can take hours adding greatly to the expense of shipping and handling.
In heavy seas, waves can wash over the side of the boat creating a potential water damage problem for these dry powder drilling materials. When product is damaged on the way out to sea and to the drilling rig, it is damage that is not always discovered until the vessel arrives, creating a waste of time and money for the boat operator and for the rig operator. If damaged inventory is extensive, insufficient mud production can shut down drilling operations with enormous associated cost to the operator.
Once a work boat arrives on location, the product must be lifted by crane onto the drilling rig, one pallet at a time. Sometimes, the pallets that are needed for a particular job are the last ones to be unloaded from the vessel because the vessel is unloaded in reverse order. If a particular product is urgently needed, it may not be able to be obtained until several hours of unloading have passed.
When dry packaged drilling products do arrive on location, they are typically stored and sometimes for an extended period of time before use. On land drilling locations, the pallets are stacked in the most convenient spot on the board road. Offshore, such sacks of dry material occupy any available deck space. When a particular product is needed, a pallet load of that product is located and positioned near an appropriate hopper using a fork truck or crane and in some cases hand carrying is used.
At the particular hopper, the sacks of dry material must literally be cut open by hand and dumped. This is an unsafe process with many inherent risks. Back injuries, lacerations, and dust irritation are common problems associated with the handling of twenty-five to one hundred pound sacks of dry drilling material.
Once all the dry material is added to the hopper, the empty sacks are collected and placed in a trash bin along with shrink wrap, broken wooden pallets, all of which must be returned to shore for disposal at additional expense. A source of environmental concern is that waste is lost at sea due to weather conditions or deliberately cast off to avoid disposal cost. This creates a pollution problem for the open seas and the shore lines. It has been estimated that ten percent of the average total of dry material cost is due to lost product through mishandling and weather conditions and related damage.